The development of a cost-effective leukodepletion system for fresh whole blood is proposed that will have four important characteristics. The system will 1) provide a 4-5 log leukocyte removal efficiency, 2) allow for the recovery of at least 80-90 percent of platelets in a viable form, 3) be capable of recovering greater than 90 percent red blood cells, and 4) will reduce processing time by a factor of 5. The heart of the system will be a leukodepletion device that will be designed using a proprietary Continuous-Gradient Flow Management (CGFM) design strategy developed at Synosys, Inc. The CGFM method follows an empirically derived rational design strategy to maximize flow rate for a desired leukodepletion efficiency and leukocyte capacity. The device will be the disposable element in a leukodepletion system designed to process fresh whole blood rapidly in a safe and cost-effective manner. The ability to leukodeplete fresh whole blood with a single device will eliminate the need for individual leukodepletion steps used today for blood components, this, providing blood products of superior quality at lower cost. PROPOSED COMMERCIAL APPLICATION This device would allow for the cost-effective leukodepletion of blood collected for transfusions (13 Million Units per year in the US alone).